There are a number of medicament delivery devices on the market that are capable of delivering a certain prescribed dose that has been set by the user before dose delivery. This feature of the medicament delivery devices is practical in many instances because the same type of medicament delivery device may be used for different types of drugs, for patients with different needs and thus for different dose sizes such as for children or for adults and/or for medicament administration schemes that vary over time. Instead of having specific designs delivering certain fixed dose amounts, a certain dose may be set by the patient directly before dose delivery. The feature of setting specific doses is also practical with multi-dose injection devices, which are capable of delivering a number of specified, set, doses until the compartment is empty. One example is disclosed in the European patent application publication EP1218042, where specific doses can be set before injection by turning a dose setting button on the distal end of the injector.
If however a dose is set too high, i.e. the user overshoots the desired dose, the device has to be reset so that a user may set the proper dose. According to EP1218042 this is done by continuing the rotation of the dose setting knob until it is moved past the maximum value, past which the dose setting knob is released. It is then possible to rotate back the dose setting knob to the initial, or zero, position, at which position the dose setting knob is re-connected to the dose setting mechanism.
A clear drawback with the solution according to EP1218042 is that if the dose is overshot, the dose knob has to be rotated the whole way to the end position and then rotated back to the zero position, and then again turned to the desired dose. Thus, if a dose setting is missed a lot of rotation is required in order reset the device and set the dose. Further, the design requires a substantial number of interacting components in order to achieve the desired function.
There is thus room for improvements regarding this type of medicament delivery device.